Explanation/Reference:
Explanation:
MatchCollection

Represents the set of successful matches found by iteratively applying a regular expression pattern to the input string.
The collection is immutable (read-only) and has no public constructor. The Regex.Matches method returns a MatchCollection object.
List<T>.Add Method

Adds an object to the end of the List<T>.
Incorrect Answers:
B: The MatchCollection.GetEnumerator method returns an enumerator that iterates through a collection.
However, To iterate through the members of the collection, you should use the collection iteration (foreach) instead of retrieving the enumerator that is returned by the GetEnumerator method.
References: https://msdn.microsoft.com/en-us/library/system.text.regularexpressions.matchcollection (v=vs.110).aspx